X-ray inspection systems, e.g., baggage scanners, are commonly used to detect and prevent the passage of prohibited items beyond a security checkpoint. Such x-ray inspection systems are typically used at airports, courthouses and other locations where security is necessary or desirable. These inspection systems guard against items such as weapons and explosives from entering the restricted area. Generally, objects are placed on a conveyor and pass through the system at which time they are x-rayed. An x-ray image of the object appears on a monitor and is viewed by an operator.
Regardless of the technology used in x-ray inspection systems, the performance of such systems in large part relies on the vigilance and skillfulness of the system operators who examine x-ray images of the contents of baggage on the system's video monitor. In turn, the vigilance and skillfulness of the system operators generally depend on the amount and type of training they receive. This is very important since operator performance is critical to the overall integrity of security inspection systems.
Traditional methods of training and certifying system operators have involved training and testing in a classroom environment, with the use of photographs, slide projectors and perhaps computer-generated images. For example, photographs of video monitor images showing a weapon or other threat have been used to educate system operators on how a threatening object might appear on the system video monitor. After receiving such classroom training, system operators have then typically been tested in the same classroom setting. However, a classroom environment for training and testing is typically very different from the actual setting in which operators must detect prohibited items for at least several reasons.
First, in the classroom environment, the system operator typically sits in a chair and looks at various photographs and other materials. This does not accurately replicate real life conditions whereby the system operator must continuously watch the system's video monitor, stop and start the system and deal with disturbances. Furthermore, real life conditions involving a steady stream of people passing through a security checkpoint at an airport, many of whom may be hostile because they are late for their flights, are not typically replicated in a classroom environment. So despite a system operator's passing a classroom test with high marks, that is no guarantee of good performance by that operator in the field.
Second, the classroom environment does not effectively teach or test the operator's vigilance, i.e., focus and attention span, over time. As noted above, the system operator's vigilance is integral to the ongoing success of the security inspection process. Indeed, high vigilance during the early portion of an operator's shift during which time no threatening objects pass through undetected does not excuse a decline in attention and focus during the later portion of that operator's shift during which time a threatening object passes through.
Third, other realities of classroom training further reduce its effectiveness. To this end, classroom training and testing may expose system operators to a smaller variety of images and threats than the operator would see in real life situations. Furthermore, the expense and logistics of classroom training generally result in less training and testing than should occur.
For these and other reasons, classroom-based training and testing is not an optimum or even reliable method of training, testing and/or certifying the operators of x-ray inspection systems. In view of these shortcomings, other training tools have been developed.
One such tool is Threat Imaging Projection (TIP) technology. With TIP technology, x-ray images of threat objects are generally merged into the image of non-threat baggage that are displayed on the system's monitor. The threat images are selected at random from a library of various types of prohibited items. An operator's performance in detecting threats, missing threats and creating false alarms (detecting what is believed to be a threat when there actually is no threat) are then recorded.
Initial TIP technology implementations were limited to simply blending x-ray images of threats into the stream of baggage images. If the operator detected the threat and activated the appropriate control, the threat object was erased and feedback was provided to the operator indicating that he or she had successfully detected the threat. However, such TIP implementations never adequately worked in the field.
For example, TIP technology could not be efficiently used at actual checkpoints because the images generated by the TIP technology for training purposes would generally be indistinguishable from true threats. Where the TIP technology was set up to be automatic, i.e., without input to help distinguish between test and true threats, operators often reacted to test threats as though a true threat actually existed. For example, an operator's detecting a test threat image representing a bomb has resulted in that operator calling a bomb squad. These types of events resulted in large costs, delays and inconvenience. Where human supervisors were used to overcome problems associated with automatic testing, the testing method still proved to be cumbersome and ineffective due to cost, logistical problems and potential coaching of the operator by the supervisor.
More recently, a TIP process was developed that was somewhat more successful to a limited degree. This more recent process: 1) employed automatic testing, 2) avoided the above-mentioned costs and delays by providing sufficient feedback to the operator to avoid the situation where a test threat was treated as a true threat and 3) recorded individual operator performance in detecting threats so as to track performance over extended periods.
However, there still existed no method for using the information provided by testing with the use of TIP technology in order to certify operators. Indeed, varying uses and interpretation of the data in different segments of the security inspection industry results in varying levels of system operator proficiency and hardly any type of uniform certification method. Accordingly, there exists a serious need for a structured, uniform process for certifying system operators.